Supporters of the al-Nusra Front protest in Aleppo, Syria, on Sept. 26, days after airstrikes there targeted the al-Qaida unit called Khorasan. U.S. officials say some top Khorasan leaders were embedded with the Nusra Front, al-Qaida's arm in Syria. Fadi al-Halabi/AFP/Getty Images hide caption

itoggle caption Fadi al-Halabi/AFP/Getty Images

In January, this Free Syrian Army fighter stood in front of graffiti in Aleppo that read, roughly, "down with the Islamic State of Iraq and the Levant." On Monday, al-Qaida's leadership said it has no ties with that jihadist group. Jalal Alhalabi /Reuters/Landov hide caption

itoggle caption Jalal Alhalabi /Reuters/Landov